JP2013164003A - Engine cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether there is anything unusual in a cooling liquid circulation state in an outside passage for allowing a cooling liquid for a water jacket for an engine to be extracted and then returned.SOLUTION: An engine cooling device includes: an engine outside passage for allowing a cooling liquid for a water jacket of an engine to be extracted and then returned; a control valve for controlling a circulation amount of the cooling liquid for the water jacket; an electric water pump for circulating the cooling liquid; and a control part for controlling the electric water pump. The control part determines whether there is anything unusual in a cooling liquid circulation state in an outside passage based on a change in a rotation speed of the electric water pump when a driving duty of the electric water pump is constant.

Description

  The present invention relates to an external passage of an engine for taking out and returning a coolant from an engine water jacket, a control valve for controlling a coolant flow rate of the water jacket, and an electric water for flowing the coolant. The present invention relates to an engine cooling device including a pump and a control unit that controls the electric water pump.

  For example, Patent Document 1 discloses an abnormality detection device that detects an operation abnormality of a thermostat provided in a passage through which engine coolant is circulated. The thermostat operates to close the passage when the temperature of the cooling water in the passage is lower than a predetermined temperature and open the passage when the temperature is equal to or higher than the predetermined temperature.

  In Patent Document 1, when the temperature of the cooling water is lower than a predetermined temperature, that is, when the thermostat is operating normally, the cooling water in the passage is closed in a state where the electric pump is not operating in a closed state. The first pressure is detected by the pressure sensor, and after waiting for a period from when the electric pump is operated until it reaches a steady state, the second pressure of the cooling water in the passage is detected by the pressure sensor.

  If the result of subtracting the first pressure from the second pressure is higher than the first reference value, it is determined that the thermostat is abnormal unless the thermostat is opened and closed, whereas if the result is lower than the first reference value. It is determined that the thermostat is operating normally and closed.

JP 2006-233809 A

  In the above-mentioned Patent Document 1, it is determined whether or not the thermostat has an open failure (a failure that does not move while being open). As the determination logic, the first cooling water in the passage during the operation of the electric pump is used. Since the difference between the pressure and the second pressure of the cooling water when the electric pump is not in operation is examined, there is a concern that the equipment cost will increase, such as the need to newly install a pressure sensor.

  In view of such circumstances, the present invention provides an external passage of the engine for taking out and returning the coolant of the engine water jacket, a control valve for controlling the coolant flow rate of the water jacket, and the coolant. In an engine cooling device including an electric water pump for flowing and a control unit for controlling the electric water pump, it is determined whether there is an abnormality in the coolant flow state in the external passage without increasing the number of components. The purpose is to make it possible.

  An engine cooling apparatus according to the present invention includes an external passage of an engine for taking out and returning a coolant of an engine water jacket, a control valve for controlling a coolant flow rate of the water jacket, and a flow of the coolant. An electric water pump for controlling the electric water pump, and a control unit for controlling the electric water pump, wherein the control unit changes the rotational speed of the electric water pump when the driving duty of the electric water pump is constant. The presence or absence of an abnormality in the coolant flow state in the external passage is determined based on the above.

  The abnormality in the coolant flow state in the external passage includes that the control valve is malfunctioning or the passage is clogged. The malfunction of the control valve includes a closed failure in which the control valve does not operate with the valve closed.

  In such a configuration, when an abnormality occurs in the coolant flow state, it is possible to recognize this with a relatively simple control logic, thereby suppressing an increase in equipment cost of the engine cooling device. It becomes possible to do.

  Preferably, the external passage is provided with an electric water pump on the way and a radiator passage for returning the coolant discharged from the two water jackets to the two water jackets through the radiator, and the radiator passage to the radiator passage. A radiator bypass path connected so as to bypass the radiator, and a radiator thermostat provided between the radiator passage in the coolant flow direction downstream side of the radiator and a downstream side connection portion of the radiator bypass path. It can be configured.

  Here, the configuration of the external passage is specified. By this specification, the flow path of the coolant becomes clear.

  Preferably, a temperature sensor that detects the temperature of the coolant near the coolant introduction part as the engine outlet coolant temperature and inputs it to the control part is installed near the coolant introduction part of the radiator passage. It can be configured.

  Here, the arrangement of the temperature sensor for detecting the engine outlet coolant temperature is specified. Since the coolant introduction part of the radiator passage is a place immediately after the coolant is taken out from the water jacket, the coolant temperature near the coolant recirculation part can be said to be the engine outlet coolant temperature.

  Preferably, the control valve is a thermostat that opens and closes according to a level of a coolant temperature, and the control unit is configured so that the engine outlet coolant temperature is lower than the valve opening temperature of the thermostat and the valve opening temperature. When the number of rotations of the electric water pump driven by a PWM signal having a constant duty ratio is detected and the difference between the detected rotation numbers is equal to or less than a predetermined value It can be configured to recognize that the control valve is closed.

  The thermostat means a temperature sensing type automatic opening / closing valve in the automotive industry. In this case, a control logic for opening and closing the control valve by the control unit is not necessary, and it is possible to contribute to a reduction in equipment cost.

  By the way, for example, when the electric water pump is driven by a PWM signal having a constant duty ratio while the control valve is closed, the control valve is installed when the control valve is normally opened. Since the cross-sectional area of the passage is increased, the pressure loss is reduced and the rotational speed of the electric water pump is increased. However, if the control valve is not opened due to malfunction, the rotational speed of the electric water pump hardly changes.

  Thus, if the change in the rotational speed of the electric water pump is examined at the timing when the control valve is switched from the closed state to the open state or vice versa, it is possible to recognize whether or not the control valve is malfunctioning.

  Preferably, the control valve is opened or closed in response to a switching signal, and the control unit is driven by a PWM signal having a constant duty ratio before and after the switching signal is input. Detecting the number of rotations of the electric water pump, and recognizing that the control valve is in a closed failure when the difference between the detected numbers of rotations is equal to or less than a predetermined value. Can do.

  The control valve here is not an automatic opening / closing valve such as the thermostat but a valve that is actuated by the input of an electrical switching signal.

  By the way, for example, when the electric water pump is driven by a PWM signal having a constant duty ratio while the control valve is closed, the control valve is installed when the control valve is normally opened. Since the cross-sectional area of the passage is increased, the pressure loss is reduced and the rotational speed of the electric water pump is increased. However, if the control valve is not opened due to malfunction, the rotational speed of the electric water pump hardly changes.

  In this way, if the change in the rotational speed of the electric water pump is examined before and after the input of the switching signal from the closed state to the open state or vice versa, the presence or absence of malfunction of the control valve can be recognized. Is possible.

  The present invention relates to an external passage of an engine for taking out and returning a coolant from an engine water jacket, a control valve for controlling a coolant flow rate of the water jacket, and an electric water for flowing the coolant. In an engine cooling device that includes a pump and a control unit that controls the electric water pump, it is possible to determine whether there is an abnormality in the coolant flow state in the external passage without increasing the number of components. Therefore, the engine cooling device can be provided at a relatively low cost.

It is a figure showing typically composition of one embodiment of an engine cooling device concerning the present invention. When the electric water pump of FIG. 1 is driven by a PWM signal having a constant duty ratio, the change in the rotational speed of the electric water pump with respect to the change in the pressure loss in the external passage (block side coolant recirculation portion 7b of the radiator passage 7). It is a graph which shows. It is a flowchart used for the description regarding the abnormality diagnosis of the control valve by the control part of FIG. It is a timing chart in case the control valve is normal in embodiment of FIG. It is a timing chart in case the control valve is abnormal in the embodiment of FIG. It is a flowchart used for description regarding abnormality diagnosis in another embodiment of the engine cooling device according to the present invention when the control valve is an electronic thermostat. It is a timing chart in case the control valve is normal in the embodiment of FIG. It is a timing chart in case the control valve is abnormal in the embodiment of FIG.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  1 to 5 show an embodiment of the present invention. The engine 1 shown in this embodiment is provided with an internal passage of the engine and an external passage of the engine as a coolant circulation path for taking out the coolant and returning it to the outside.

  The internal passage includes a water jacket 4 provided in the cylinder block 2 of the engine 1 and a water jacket 5 provided in the cylinder head 3 of the engine 1. The external passage includes at least a radiator passage 7 and a radiator bypass passage 8.

  The coolant discharge part 5a of the water jacket 5 in the head is provided on the other end surface (for example, the rear end surface) of the cylinder head 3 in the cylinder arrangement direction. The coolant recirculation part 5b of the water jacket 5 in the head is provided on one end surface (for example, the front end surface) of the cylinder head 3 in the cylinder arrangement direction.

  The coolant recirculation part 4a of the water jacket 4 in the block is provided below the one end surface (for example, the front end surface) in the cylinder arrangement direction in the cylinder block 2. The downstream side of the in-block water jacket 4 is connected to the upstream side of the in-head water jacket 5. That is, the coolant discharge part 5 a of the head water jacket 5 also serves as the coolant discharge part of the block water jacket 4.

  A radiator passage 7 is connected to the coolant discharge portion 5a of the water jacket 5 in the head, the coolant return portion 4a of the water jacket 4 in the block, and the coolant return portion 5b of the water jacket 5 in the head.

  The radiator passage 7 circulates the coolant discharged from the coolant discharge portion 5 a of the head water jacket 5 to the head water jacket 5 and the block water jacket 4.

  One end side of the radiator passage 7 (upstream end side in the coolant flow direction) is a single coolant introduction portion 7a, but the other end side (downstream end side in the coolant flow direction) of the radiator passage 7 is It is bifurcated. Of the two branched branch parts, one is a block-side coolant reflux part 7b and the other is a head-side coolant reflux part 7c.

  One coolant introduction part 7 a of the radiator passage 7 is connected to the coolant discharge part 5 a of the head water jacket 5. The block-side coolant recirculation part 7b of the radiator passage 7 is connected to the coolant recirculation part 4a of the water jacket 4 in the block, and the head-side coolant recirculation part 7c of the radiator passage 7 is connected to the water jacket 5 in the head. Is connected to the coolant recirculation part 5b.

  The radiator passage 7 is provided with a radiator 11 and an electric water pump 12.

  The radiator 11 exchanges heat between the coolant flowing through the radiator passage 7 and the atmosphere, and is mainly a heat exchanger for cooling. The electric water pump 12 causes the coolant to flow in the radiator passage 7 and the radiator bypass passage 8 described below. For example, the electric water pump 12 is provided upstream of the bifurcated branch portion of the radiator passage 7 in the coolant flow direction. .

  The electric water pump 12 has a PWM (Pulse Width Modulation) circuit (not shown) and is PWM-controlled by a control signal supplied from an electronic control unit (hereinafter simply referred to as ECU) 100 described below.

  The ECU 100 increases the rotational speed of the pump motor of the electric water pump 12 (simply referred to as the rotational speed of the water pump 12) by increasing the duty ratio of the PWM signal supplied to the pump motor of the electric water pump 12. The torque applied to the shaft of the pump motor can be increased. On the contrary, if the duty ratio is reduced, the rotational speed of the electric water pump 12 can be reduced, and the torque applied to the shaft of the pump motor can be reduced.

  The radiator bypass path 8 is connected to the radiator passage 7 so as to bypass the radiator 11. A heater core 13 is provided in the middle of the radiator bypass 8.

  The heater core 13 is a heat exchanger for exchanging heat between the coolant flowing through the radiator bypass 8 and the vehicle compartment. The heat released from the heater core 13 is supplied to the vehicle interior by a heater blower (not shown) to heat the vehicle interior. The operation of the heater blower is controlled by the ECU 100.

  A radiator thermostat 21 is provided in the radiator passage 7 at a position downstream of the radiator 11 in the coolant circulation direction and upstream of the downstream connecting portion of the radiator bypass passage 8 in the coolant circulation direction. .

  Since this radiator thermostat 21 has a known configuration, a detailed illustration and description thereof are omitted, but generally includes a valve body and a thermoactuator. The thermoactuator includes a temperature sensing part filled with thermowax, and a plunger provided in the temperature sensing part to displace the valve body in the valve opening direction or the valve closing direction.

  Here, the operation of the radiator thermostat 21 will be described. In the radiator passage 7, when the coolant temperature at the downstream connection portion with the radiator bypass passage 8 is lower than the overheat prevention temperature, the thermowax is solidified and contracted and the wax pressure is lowered, so that the plunger is connected to the temperature sensing portion. And the valve body is displaced to the fully closed position. In addition, the said overheat prevention temperature is set to the arbitrary value higher than warming-up completion temperature (for example, 85 to 90 degreeC, Preferably 88 degreeC). When the coolant temperature becomes equal to or higher than the overheat prevention temperature, the thermowax is melted and expanded to increase the wax pressure, so that the plunger jumps out of the temperature sensing portion and opens the valve body. . As a result, the coolant flows through both the radiator passage 7 and the radiator bypass passage 8.

  In this embodiment, the control valve 22 is provided in the block side coolant recirculation part 7 b of the radiator passage 7.

  The control valve 22 is a normally closed type thermostat, and blocks or allows the coolant flow in the block-side coolant return unit 7b. The control valve 22 can also restrict the coolant flow.

  Since the thermostat as the control valve 22 has basically the same configuration as the above-described radiator thermostat 21, a detailed description and explanation are omitted. However, the thermostat includes a valve body and a thermoactuator. The thermoactuator includes a temperature sensing part filled with thermowax, and a plunger provided in the temperature sensing part to displace the valve body in the valve opening direction or the valve closing direction.

  Here, the operation of the thermostat as the control valve 22 will be described. When the coolant temperature thw upstream of the control valve 22 in the coolant circulation direction in the block side coolant recirculation unit 7b is less than a predetermined valve opening temperature X, the thermowax is solidified and contracted to reduce the wax pressure. The body is automatically closed to stop the flow of the coolant from the radiator passage 7 to the water jacket 4 in the block. The valve opening temperature X is set to an arbitrary value that is higher than the warm-up completion temperature and lower than the overheat prevention temperature. When the coolant temperature thw becomes equal to or higher than the valve opening temperature X, the thermowax is melted and expanded to increase the wax pressure, so that the valve body is automatically opened and the water jacket 4 in the block is passed through the radiator passage 7. Let the coolant flow into the tank.

  The ECU 100 is, for example, an engine control computer for executing various controls of the engine 1. In this embodiment, the existing ECU 100 has a function of controlling the operation of the electric water pump 12 and a function of diagnosing whether or not an abnormality of the control valve 22 (a closed failure that causes a malfunction in the closed state) has occurred. Is equipped. The ECU 100 corresponds to a “control unit” recited in the claims.

  Although not shown in detail, the ECU 100 has a known configuration including a CPU (central processing unit), a ROM (program memory), a RAM (data memory), a backup RAM (nonvolatile memory), and the like.

  The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores calculation results in the CPU, data input from each sensor, and the like. The backup RAM is a nonvolatile memory that stores data to be saved when the engine 1 is stopped, for example. Memory.

  As described above, in this embodiment, an appropriate closed-loop coolant circulation path is formed by the internal passages (water jackets 4 and 5) of the engine 1 and the external passages (radiator passage 7 and radiator bypass passage 8). The internal passage, the external passage, the electric water pump 12, the radiator thermostat 21, the control valve 22, and the ECU 100 constitute an engine cooling device.

  The ECU 100 adjusts the temperature of the engine 1 by controlling the operation of the electric water pump 12 and the like based on the detection output input from the temperature sensor 31, for example. The temperature sensor 31 is provided near the coolant introduction part 7a of the radiator passage 7 (near the coolant discharge part 5a of the water jacket 5 in the head), and the coolant temperature thw (engine outlet coolant temperature at the installation location). (Also called).

  Specifically, the basic operation by the engine cooling device of this embodiment will be described.

  For example, when the engine 1 is cold started, that is, when the detection output of the temperature sensor 31 (engine outlet coolant temperature thw) when the engine 1 is started is less than a predetermined cold start determination reference value, the ECU 100 Instruct the pump 12 to deactivate. The cold start determination reference value is set to an arbitrary value lower than the warm-up completion temperature.

  Since the radiator thermostat 21 and the control valve 22 comprising the thermostat are both closed until the predetermined time has elapsed since the cold start, the coolant does not flow in the water jackets 4 and 5 and stops. To come. As a result, the temperature of the coolant in the engine 1 and the water jackets 4 and 5 is promoted by heat generated from the cylinder head 3, particularly from the combustion chamber.

  Thus, after the coolant in the engine 1 and the water jackets 4 and 5 rises in temperature, the engine outlet coolant temperature thw becomes equal to or higher than the cold start determination reference value, and then the in-head water jacket is reached. When the ECU 100 detects that the temperature of the coolant has excessively increased (boiling) in the region 5 (near the cylinder head combustion chamber), the ECU 100 instructs the electric water pump 12 to operate.

  As an example of the method for detecting the excessive temperature rise, the maximum coolant temperature in the region where the maximum temperature in the cylinder head 3 is reached in the water jacket 5 in the head every predetermined cycle (several milliseconds) from the start of the engine 1. This can be done by estimating the value. As an example of this estimation method, the process of recognizing the initial value of the engine outlet coolant temperature thw based on the detection output from the temperature sensor 31 at the start of the engine 1 and the engine 1 after the engine 1 is started A process of calculating the amount of generated heat, calculating a rise value of the maximum temperature reaching region in the cylinder head due to the amount of generated heat, and adding the rise value to a previous estimated value (the initial value is the initial value) to A process of estimating the current coolant temperature in the region where the maximum temperature in the head is reached and a process of determining that boiling occurs when the estimated value exceeds a predetermined temperature (for example, 96 ° C.) are performed. .

  When the electric water pump 12 is operated as described above, the coolant in the head water jacket 5 is discharged from the coolant discharge portion 5a to the radiator passage 7 as shown by the solid arrows in FIG. Instead of flowing into the radiator 11, it flows through the radiator bypass path 8, flows into the head side coolant recirculation unit 7 c, and further flows into the head water jacket 5.

  In this way, when the coolant repeatedly flows through the water jacket 5 in the head, the coolant absorbs heat of the cylinder head 3 particularly in the vicinity of the combustion chamber. As a result, the coolant is prevented from excessively rising (boiling) locally in the water jacket 5 in the head, while the coolant in the cylinder block 2 and the water jacket 4 in the block is gradually heated. Become. As a result, the temperature rise is promoted while keeping the temperature difference between the cylinder block 2 and the cylinder head 3 as small as possible.

  By the way, when the engine outlet coolant temperature thw becomes equal to or higher than the valve opening temperature X of the control valve 22, the control valve 22 is automatically opened. When this control valve 22 is opened, the coolant discharged from the coolant discharge portion 5a of the water jacket 5 in the head to the radiator passage 7 from the radiator bypass passage 8 to the head side, as shown by the one-dot chain line arrow in FIG. Since it flows into both the cooling liquid recirculation part 7c and the block side cooling liquid recirculation part 7b, it flows into the water jacket 5 in the head and the water jacket 4 in the block. As a result, a sufficient amount of coolant is circulated between the radiator bypass path 8 of the radiator passage 7 and the water jacket 4 in the block and the water jacket 5 in the head.

  Thereafter, when the coolant temperature in the downstream passage portion of the radiator passage 7 with the radiator bypass passage 8 becomes equal to or higher than the overheat prevention temperature, the radiator thermostat 21 is automatically opened. As indicated by a chain line arrow, the coolant discharged from the coolant discharge portion 5 a of the head water jacket 5 to the radiator passage 7 flows not only to the radiator bypass path 8 but also to the radiator 11. Then, the coolant that has passed through the radiator bypass path 8 and the radiator 11 is returned to the head water jacket 5 and the block water jacket 4. In this way, the coolant discharged from the engine 1 is circulated so as to be returned to the water jackets 4 and 5 after being cooled by the radiator 11, so that the circulating coolant and the temperature of the engine 1 are within a certain range. Thus, overheating of the engine 1 is avoided and the temperature is maintained at an appropriate temperature.

  In this embodiment, the ECU 100 performs an abnormality (closed fault) diagnosis of the control valve 22 and will be described below.

  As described above, when the coolant temperature rises to the valve opening temperature from the state in which the control valve 22 is closed, the valve is opened if the control valve 22 is normal. As a result, the cross-sectional area of the block-side coolant recirculation portion 7b of the radiator passage 7 is increased, so that the pressure loss is reduced. However, the electric water pump 12 is driven at a constant duty ratio before and after the control valve 22 is switched. As a result, the rotational speed of the electric water pump 12 naturally increases. Incidentally, as shown in FIG. 2, when the electric water pump 12 is driven at a constant duty ratio (for example, maximum or minimum), the rotation of the electric water pump 12 decreases as the pressure loss in the coolant flow path decreases. As the number increases and the pressure loss in the coolant flow path increases, the rotational speed of the electric water pump 12 tends to decrease.

  However, when the closed failure that causes the malfunction occurs while the control valve 22 is in the closed state, the rotational speed of the electric water pump 12 hardly changes.

  Thus, when the control valve 22 is closed, a phenomenon that is clearly different from the normal state occurs as described above. The inventor of the present application makes it possible to determine whether or not the control valve 22 is abnormal based on such knowledge.

  Specifically, referring to FIG. 3 to FIG. 5, the abnormality (closed fault) diagnosis of the control valve 22 performed by the ECU 100 will be described in detail.

  This flowchart shows the processing by the ECU 100, and is started when, for example, an ignition key or a power switch is turned on to supply power to the ECU 100.

  When this flowchart is started, first, in step S1, the monitoring process for detecting the engine outlet coolant temperature (the coolant temperature thw recognized based on the detection output of the temperature sensor 31) is started.

  In the subsequent step S2, it is determined whether or not the current engine outlet coolant temperature thw recognized in the monitoring process in step S1 is lower than the valve opening temperature X of the control valve 22.

  Here, if the current engine outlet coolant temperature thw is lower than the valve opening temperature X of the control valve 22, that is, if thw <X, an affirmative determination is made in step S2, and the process goes to steps S5 through S3 and S4. Transition.

  On the other hand, if the current engine outlet coolant temperature thw is equal to or higher than the valve opening temperature X of the control valve 22, that is, if thw ≧ X, a negative determination is made in step S2, and the process proceeds to step S5 via step S6.

  First, the processing of steps S3 to S5 will be described. In step S3, the actual rotational speed R1 when the electric water pump 12 is driven with a PWM signal having a predetermined duty ratio while the control valve 22 is closed is acquired, and the acquired information is stored in a backup RAM or the like. Save to.

  In subsequent step S4, it is determined whether or not the current engine outlet coolant temperature thw is equal to or higher than the valve opening temperature X of the control valve 22. Here, if the current engine outlet coolant temperature thw is lower than the valve opening temperature X of the control valve 22, that is, if thw <X, a negative determination is made in step S4 and the process returns to step S2. If the engine outlet coolant temperature thw is equal to or higher than the valve opening temperature X of the control valve 22, that is, if thw ≧ X, an affirmative determination is made in step S4 and the process proceeds to step S5.

  In this step S5, the actual rotational speed R2 of the electric water pump 12 driven by the PWM signal with the duty ratio is acquired as the control valve 22 is opened, and the acquired information is backed up. Save to RAM or the like. Thereafter, the process proceeds to the following step S7.

  By the way, in the step S6, information on the previous trip stored in the backup RAM (the rotational speed R0 of the electric water pump 12 driven by a PWM signal having a predetermined duty ratio when the control valve 22 is closed) is stored. read out. Thereafter, the process proceeds to step S5.

  The one-time trip is, for example, from when the power is turned on by an ignition key or a power switch until the power is turned off. That is, the information finally rewritten and stored in the backup RAM when the power is turned off (the rotational speed R0 of the electric water pump 12 driven by a PWM signal having a predetermined duty ratio when the control valve 22 is closed). Is used in the next trip (for example, step S6).

  Next, in step S7, the rotational speed (R1, R0) of the electric water pump 12 when the control valve 22 is closed and the rotational speed (R2) of the electric water pump 12 when the control valve 22 is open. It is checked whether or not the deviation value is less than a predetermined value.

  Specifically, in step S7, the information stored in the backup RAM in step S5 (the rotational speed R2 of the electric water pump 12 driven with the PWM signal having a predetermined duty ratio after the control valve 22 is opened). From the information stored in the backup RAM in step S3 (the rotational speed R1 of the electric water pump 12 to which a PWM signal having a predetermined duty ratio is supplied) or the information read in step S6 (when the control valve 22 is closed) It is examined whether or not the result of subtracting the rotational speed R0 of the electric water pump 12 to which the PWM signal having the predetermined duty ratio is supplied is equal to or less than the predetermined threshold Y.

  The threshold value Y is set on the assumption that the control valve 22 is closed. That is, when the control valve 22 is closed, the rotational speed of the electric water pump 12 hardly changes between when the valve is closed and after the valve is opened, so the threshold value Y can be zero. Here, it is set by adding a margin α corresponding to an appropriate error.

  Here, as shown in FIG. 4C, when the rotational speed of the electric water pump 12 rises after the valve opening temperature of the control valve 22 is reached, R2-R1 (or R0)> Y Therefore, a negative determination is made in step S7, and in step S8, the control valve 22 is determined to be “normal”, and this flowchart is ended.

  On the other hand, as shown in FIG. 5C, when the rotational speed of the electric water pump 12 hardly changes after the control valve 22 reaches the valve opening temperature or higher, R2−R1 (or R0) ≦ Y Therefore, an affirmative determination is made in step S7, and in step S9 it is determined that the control valve 22 is “abnormal (closed failure)”, and this flowchart is ended.

When it is determined that the control valve 22 is abnormal, the determination result, that is, information indicating that the control valve 22 is abnormal can be stored in the backup RAM (not shown) as a diagnosis code, for example. . In this way, the maintenance operator can easily check what the repair object is by reading the diagnosis code from the backup RAM (not shown) by diagnosis. In the embodiment to which the invention is applied, the presence or absence of an abnormality in the control valve 22 (a closed failure that causes a malfunction in the closed state) is relatively simple without using a pressure sensor as in Patent Document 1 described in the conventional example. It is possible to make a determination only with simple control logic. Thereby, compared with the said patent document 1, it becomes possible to provide an engine cooling device comparatively cheaply.

  In addition, in this embodiment, when it is recognized that an abnormality has occurred in the control valve 22, information related to the abnormality is stored. Therefore, by examining the stored information, the contents to be repaired are determined. It becomes possible to recognize easily.

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) Although the example which made the control valve 22 the thermostat is given in the said embodiment, this invention is not limited to this.

  For example, the control valve 22 may be a control valve that operates upon receiving an operation instruction from the ECU 100, for example. Specifically, examples of this type of control valve 22 include an electronic thermostat, a solenoid valve, or an electric valve operated by a motor or the like that can heat the thermo-wax of the temperature sensing portion with a heater or the like. It is done.

  The abnormality diagnosis in the case of such a control valve 22 is shown in the flowchart of FIG. 6 is different from the flowchart shown in FIG. 3 in that step S21 in FIG. 6 corresponds to step S1 in FIG. 3, step S22 in FIG. 6 corresponding to step S2 in FIG. 3, and FIG. This is the processing content of step S24 in FIG. 6 corresponding to step S4. Note that steps S23 and S25 to S29 in FIG. 6 are basically the same as the processing contents of steps S3 and S5 to S9 in FIG.

  Specifically, in step S21, it is monitored that a signal for switching the control valve 22 to an open state or a closed state is input. In steps S22 and S24, it is checked whether or not a signal for switching the control valve 22 to the open state or the closed state is input.

  If it is determined in step S22 that no switching signal is input, the process proceeds to step S23. If it is determined that a switching signal is input, the process proceeds to step S26. If it is determined in step S24 that no switching signal is input, the process returns to step S22. If it is determined that a switching signal is input, the process proceeds to step S25.

  Incidentally, for example, as shown in FIG. 7, when the control valve 22 is normally operated and opened in response to the input of the switching signal from the closed state to the open state, The rotational speed of the water pump 12 will increase. However, for example, as shown in FIG. 8, when the control valve 22 is switched from the closed state to the open state, if the control valve 22 is closed and does not open, The rotation speed of the pump 12 hardly changes.

  Even in the case of the embodiment described here, basically, as in the above-described embodiment, whether or not there is an abnormality in the control valve 22 (a closed failure that causes a malfunction in the closed state) is described in Patent Document 1 described in the conventional example. Therefore, it is possible to recognize only by a relatively simple control logic without using a pressure sensor.

  (2) In the above embodiment, the presence or absence of abnormality (closed failure) of the control valve 22 is determined by examining the change in the rotational speed of the electric water pump 12 before and after the control valve 22 switches from the closed state to the open state. Although an example is shown, the present invention is not limited to this.

  For example, in a situation where the electric water pump 12 is driven with a PWM signal having a constant duty ratio, when the rotational speed of the electric water pump 12 changes, the timing at which the rotational speed change occurs is the control. When it is time to switch the valve 22 from the closed state to the open state, it can be determined that the control valve 22 is normal.

  However, when the timing at which the rotational speed change occurs during engine operation is not the timing at which the control valve 22 switches from the closed state to the open state, it is not an abnormality of the control valve 22 but an external passage (the radiator passage 7 and the radiator passage 7). Since the bypass passage 8) is clogged, it can be determined that the coolant flow state is abnormal.

  The timing at which the control valve 22 switches from the closed state to the open state can be detected based on the output of the temperature sensor 31 in the case of the embodiment shown in FIGS. In the case of the embodiment illustrated in (2), it is possible to detect based on the input of a switching signal for switching the control valve 22 to the valve open state or the valve close state.

  In the case of the embodiment described here, in addition to making it possible to detect an abnormality (closed failure) of the control valve 22, it also detects an abnormality in the coolant flow state due to clogging of the external passages (7, 8). It becomes possible to do.

  By the way, in order to perform the abnormality determination reliably even when the clogging occurs before the engine is operated, the following may be considered.

  The normal value of the rotational speed of the electric water pump 12 when the control valve 22 is closed or opened is mapped in advance for each duty ratio of the PWM signal supplied to the electric water pump 12. When the rotational speed of the electric water pump 12 when the control valve 22 is closed or opened after the electric water pump 12 is driven is too high compared to the map value, the external passage (radiator passage 7 In addition, it is possible to determine that the coolant flow state is abnormal because the radiator bypass passage 8) is clogged.

  (3) In the above embodiment, an example in which the downstream side of the water jacket 4 in the block in the coolant flow direction is connected to the water jacket 5 in the head is described, but the present invention is not limited to this.

  For example, although not shown, the water jacket 4 in the block and the water jacket 5 in the head are independent from each other, that is, the coolant discharge portion of the water jacket 4 in the block is provided on the other end surface of the cylinder block 2, and the radiator passage 7 The coolant inflow side is branched into two branches, one of the branches is connected to the coolant discharge portion of the water jacket 4 in the block, and the other branch of the two branches is the coolant of the head water jacket 5. It is possible to make it the structure which connects with the discharge part 5a.

  (4) Although not shown in the above embodiment, the present invention can be applied even to a configuration in which a control valve is provided in the head side coolant recirculation part 7 c of the radiator passage 7.

  (5) In the above embodiment, an example is given in which information indicating that the control valve 22 is abnormal is stored in an appropriate memory when it is determined that the control valve 22 is abnormal. However, the present invention is not limited to this. However, the present invention includes a case where such information storage is not performed.

  The present invention relates to an external passage of an engine for taking out and returning a coolant from an engine water jacket, a control valve for controlling a coolant flow rate of the water jacket, and an electric water for flowing the coolant. The present invention can be suitably applied to an engine cooling device including a pump and a control unit that controls the electric water pump.

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 3 Cylinder head 4 Water jacket in block 4a Coolant return part of water jacket in block 5 Water jacket in head 5a Coolant discharge part of water jacket in head 5b Coolant return part of water jacket in head 7 Radiator Passage 7a Coolant introduction part for radiator passage 7b Block side coolant return part for radiator passage 7c Head side coolant return part for radiator passage 8 Radiator bypass path 11 Radiator 12 Electric water pump 21 Radiator thermostat 22 Control valve 31 Temperature sensor 100 ECU

Claims (5)

An external passage of the engine for taking out and returning the coolant of the water jacket of the engine, a control valve for controlling the coolant flow rate of the water jacket, an electric water pump for flowing the coolant, and A control unit for controlling the electric water pump,
The controller determines whether there is an abnormality in the coolant flow state in the external passage based on a change in the rotational speed of the electric water pump when the drive duty of the electric water pump is constant. A featured engine cooling device. The engine cooling device according to claim 1, wherein
The external passage is provided with the electric water pump in the middle and a radiator passage for returning the coolant discharged from the water jackets to the water jackets through the radiators;
A radiator bypass path connected to the radiator path to bypass the radiator;
An engine cooling device comprising: a radiator thermostat provided between a downstream side of the radiator passage in a coolant flow direction and a downstream side connecting portion of the radiator bypass passage in the radiator passage. The engine cooling device according to claim 2, wherein
A temperature sensor that detects the temperature of the coolant near the coolant introduction part as the engine outlet coolant temperature and inputs it to the control part is installed near the coolant introduction part of the radiator passage. Engine cooling device. In the engine cooling device according to any one of claims 1 to 3,
The control valve is a thermostat that opens and closes depending on the coolant temperature.
The control unit is configured to drive the electric water driven by a PWM signal having a constant duty ratio when the engine outlet coolant temperature is lower than the valve opening temperature of the thermostat and when the temperature is equal to or higher than the valve opening temperature. An engine cooling apparatus characterized by detecting the number of rotations of each pump and recognizing that the control valve has a closed failure when a difference value between the detected numbers of rotations is equal to or less than a predetermined value. The engine cooling device according to claim 1 or 2,
The control valve is opened or closed in response to a switching signal,
The controller detects the rotational speed of the electric water pump driven by a PWM signal having a constant duty ratio before and after the switching signal is input, and the difference value between the detected rotational speeds. An engine cooling device characterized by recognizing that the control valve is in a closed failure when is below a predetermined value.

Images